It is quite popular to use streaming technologies to watch video or listen to music in data communications systems. This is in particular so in wireless and mobile systems. A streaming session typically involves a client which connects to a server and chooses and controls the media via a control protocol such as RTSP (Real-Time Streaming Protocol) while the media is sent from the server to the client using RTP (Real-time Transport Protocol) over UDP (User Datagram Protocol) over IP (Internet Protocol).
However, there is a risk that the bandwidth needed for the transport of the media is not sufficient, resulting in packets being lost in the transport. This will appear as deterioration in the video quality and/or artefacts in the sound. Since such packet losses will be perceived as very bad by the users, it is important to be able to test mobile (wireless) links and also other links and measure how the network behaves for streams with various bitrates.
Today, such a test is typically done by a special test setup procedure where a dedicated testing client, such as a TEMS™ capable terminal, connects to a server and there is some monitoring of packet losses in the network or in the terminal. The monitoring is done by sniffing the network traffic, or by looking at reports sent back to the server.
However, these dedicated devices, such as TEMS™ devices, are complicated and may only be operated by trained experts. Only these experts are capable of determining the quality of the data connection by using the dedicated devices.
WO 2007/110233 discloses a digital test sequence that can be used for evaluating data communication and analyzing packet losses. The test sequence comprises an initial intra-coded picture followed by a plurality of predicted pictures. These following pictures are free from any intra-coded information. In clear contrast, the chrominance is varying between two different values for consecutive pictures in the sequence, while the luminance component is kept zero. By using the repair strategies of the decoder, packet losses can be identified in the displayed media presentation.